- Normal Sudoku rules apply except that instead of 9s you must place chess pieces. A puzzle can mix chess pieces, and in principle any piece may be used - although the rest of the constraints provide implicit limitations on which pieces may go in which squares.
- Each chess piece attacks each number from 1 to 8 precisely once.
- Attacks "pass though" numbers - see the Bishops in the second puzzle.
- Chess pieces do not attack (or protect) other chess pieces.
The space of possible puzzles is very small, and most of them are very symmetric, which makes them less interesting. Therefore I am posting two puzzles, not one: these are essentially the two distinct representatives of interesting chess Sudoku puzzles.